Sleeve valve means for two-cycle reciprocating engines



July 28, 1953 H. N. FIS ER 2,646,779

SLEEVE VALVE MEANS FOR TWO-'CYCLE RECIPROCATING ENGINES Filed Nov. 10, 1951 2 Sheer,s-Sheet 1 -INVENTOR.

7&11501,

July 28, 1953 H. N. FISER SLEEVE VALVE MEANS FOR TWO-CYCLE RECIPROCATING ENGINES Z SheetS-Sheet 2 Filed Nov. 10, 1951 llll ll I der.

Patented July 28, 1953 STATES PATENT OFFICE SLEEVE VALVE MEANS FOR TWO-CYCLE BECIPROCATIN G ENGINE S 11 Claims.

advantages was the low volumetric efficiency of g the engine due to the fact that removal of the exhaust gases was 'not complete and the amount of fuel and air mixture in the combustion chamber during the compression stroke was limited. to that which could. be held between the opposed piston heads at less than atmospheric pressure after they closed the inlet and exhaust ports, resulting in a volumetric efiiciency of less than one. Another disadvantage was the excessive consumption of oil unless the pistons carried a long skirt which sealed on the inlet and exhaust ports even when the pistons were at top dead center. This entailed the use of longer. cylinder walls below the ports than is desirable and thereby the addition of considerable excess weight and size to the engine.

An object of the present invention is to overcome these and other disadvantages common to two cycle opposed engines.

Another object of this invention is to provide means for positively evacuating the exhaust gases from the combustion chamber at the end of the power stroke so as to leave the chamber at a negative pressure with respect to the atmosphere.

Another object is to provide means for adding fuel and air mixture to the combustion chamber to build up a positive pressure therein prior to the time when the ports are closed by the cylin- A still further object is to provide oil return means whereby the long skirt necessary in the two cycle engines of the past may be eliminated and the engine size and weight may be reduced.

Generally speaking this invention provides a two cycle engine comprising an elongated cylinder chamber, a pair of pistons in said chamber mounted for reciprocation in opposite ends thereof, a pair of substantially parallel crankshafts connected to and operated by each of said pistons, a series of exhaust ports spaced apart around the cylinder chamber' adj acen't one i endof the chamber, said ports being closed by one of the pistons when the piston approaches the point of maximum entry into the chamber (top dead center), a series of intake ports apart around the cylinder chamber adjacent the end of the cylinder chamber opposite the exhaust ports, said ports being closed by the other of said pistons when said piston approaches top dead center. Positively driven means are provided for forcing either air or a fuel and air mixture through the intake ports when the piston is retracted from its position of maximum entry in the cylinder chamber. Separate positively driven means are provided for evacuating the spent gases from the exhaust ports when the piston is retracted. Valve means reciprocable along the outer wall of the cylinder chamber at either end of the cylinder open and close the exhaust and intake ports at timed intervals. Cam means on the crankshafts advance and retract the valve means. Oil return means are provided in both valve means and cooperate with means for receiving and conveying the oil to return it to the respective crankcases.

Other objects and advantages of the present invention will be apparent from the accompanying drawings in which:

Figure 1 is a partial vertical section of a two cycle engine according to my invention.

- Figure 2 is a section on the line 2-2 of Figure 1. Figure 3 is a fragmentary section on line 33 of Figure 2.

Figure 4 is a fragmentary section of the port and sleeve arrangement at the inlet port.

Figure 5 is a fragmentary section showing the cam and cam follower arrangement.

Referring to the drawings there is illustrated a preferred embodiment of this. invention in which two opposed pistons a and 50b operate in a common cylinder liner 5|. Intake ports 52 are spaced apart around the cylinder liner 5! adjacent one end thereof. Exhaust ports 53 are similarly spaced apart around the cylinder liner 5! adjacent the opposite end thereof. The intake ports 52 open into an intake manifold 54 which surrounds the cylinder liner. An exhaust manifold 55 surrounds the cylinder at the exhaust ports and communicates with them for exhausting burned gases from the cylinder liner interior. The intake piston 56a is connected through a piston rod 56 to a crankshaft 58 enclosed within a crankcase 59. connected through a piston rod 51 to a crankshaft .66 enclosed Within a crankcase 6|. .Crank- The exhaust piston 5% isv 3 shafts 58 and Bi] are connected to a main drive shaft (not shown) by a suitable gear train (not shown).

A centrifugal pump [2 driven by the engine is connected to the inlet manifold 54 for forcing air with or without fuel from the air duct l4 into the inlet manifold under a positive pressure. A similar centrifugal pump [3 is connected to the exhaust manifold 55 serving to maintain a partial vacuum in the exhaust manifold for evacuating the exhaust gases out of the cylinder liner and discharging them through exhaust line I6. Preferably the inlet centrifugal pump [2 and the exhaust pump I3 are driven by the same common shaft.

A reciprocable intake sleeve valve i1 is provided to surround the cylinder sleeve 51 for reciprocation in a valve chamber 26 to open and close the inlet ports 52. A similar reciprocable exhaust sleeve valve 18 is provided to surround the cylinder sleeve for reciprocation in a valve chamber 26a to open and close the exhaust ports 53. The inlet sleeve valve H is connected through valve rods 23 to a pair of cam followers 22 which are vertically reciprocated by a cam track ii on each side of the crankshaft 58. The exhaust sleeve is is connected through an identical pair of valve rods 23 to cam followers 22 which are likewise reciprocated by a cam track 2! on each side of the crankshaft 60. The cam followers on both the inlet and exhaust sleeves reciprocate vertically in cam guides 24 that are cut in the main bearing supports. The cam follcwers are prevented from turning by the cam lock plates 25. Preferably the arrangement of the cam tracks 2| is such that the exhaust valve it opens slightly ahead of the exhaust piston 50?) thereby uncovering the exhaust ports to prevent the ori inal rush of hot exhaust gases from striking the valve and thereby burning it and then closes the exhaust ports slightly ahead of the exhaust piston and slightly ahead of the time when the inlet piston closes the inlet ports so as to permit pressure of fuel and .air to be built up in the combustion chamber ahead of the pistons. The inlet valve H is timed to lag slightly behind the intake piston 59a to allow the exhaust ports to open first so that the exhaust pump can remove the burned gases and create a partial vacuum in the combustion chamber.

Oil return pockets it are provided in the inlet valve 5?. These oil pockets are cut into the face of the valve from a point adjacent the edge of the valve farthest removed from the crankshaft and opening through the edge of the valve nearest thc crankshaft. The pockets are slightly wider than the intake ports 52 so as to substantially cover them when the valve is in the closed position. Any oil which escapes from the cylinder liner thus is caught in the oil pockets and throvm out the open end thereof into the valve chamber 2%. Th6 oil which collects in the valve chamber is carried into the crankcase 59 by oil drain holes drilled in the cylinder wall ill.

Oil return pockets as are also provided in the exhaust valve iii. These oil return pockets 2i; differ from those in the inlet valve by being closed at all sides in order to provide a tight seal when fuel and air is being forced into the combustion chamber ahead of the pistons. Oil receiving pockets 3; (Fig. 3) are accordingly recessed in the outer wall of the cylinder sleeve 5! in line with the oil return pockets 2'8 and at a point such that the oil return pockets communioate with them when the valve is moving from about the 25% closed position to the 75% closed position. This permits th oil to be blown out of the oil return pockets 2!], through the oil receiving pockets 39 into the valve chamber 26a from which it drains into the crankcase 6! through oil drain holes 28 drilled in the cylinder wall 21.

While a preferred embodiment of this invention has been illustrated and described above it will be understood that it may be otherwise embodied within the scope of the following claims.

I claim:

1. A two cycle reciprocating engine comprising an elongated cylinder chamber, a pair of pistons in said chamber mounted for reciprocation in opposite ends thereof, a. pair of substantially parallel crankshafts connected to and operated by each of said pistons, a series of exhaust ports spaced apart around the cylinder chamber adjacent one end thereof, said ports being closed by one of the pistons when the piston approaches the point of maximum entry into the cylinder chamber, a series of intake ports spaced apart around the cylinder chamber adjacent the end of the cylinder chamber opposite the exhaust ports, said ports being closed by the other of said pistons when said piston approaches the position of maximum entry into the cylinder chamber, positively driven means forcing a fuel and air mixture through the intake ports when the piston adjacent said ports is retracted from its position of maximum entry in the cylinder chamber, positively driven means exhausting the spent gases from the exhaust ports when the piston adjacent said ports is retracted, valve means reciprocable along the outer wall of the cylinder chamber alternately to open and close the exhaust ports, cam means on the crankshaft adjacent the exhaust port end of the cylinder advancing and retracting said valve means, valve means reciproc'able along the outer wall of the cylinder chamber alternately to open and close the intake ports. means on the crankshaft adjacent the intake port end of the cylinder advancing and retracting said valve means, oil return means in both of said valve means and means receiving the oil from the oil return means and conveying it to the respective crankcases.

2. A two cycle reciprocating engine as claimed in claim 1 in which the positively driven means forcing fuel and air mixture into the cylinder chamber comprises a centrifugal pump driven by one of the engine crankshafts.

3. A two cycle reciprocating engine as claimed in claim 1 in which the positively driven means exhausting the spent gases from the exhaust ports is a centrifugal pump driven by one of the engine crankshafts and capable of forming a vacuum in the exhaust manifold.

4. A two cycle reciprocating engine as claimed in claim 1 in which the valve means at both the exhaust and intake ports are sleeve valves and the cam means includes cam surfaces cut in the crankshafts.

5. A two cycle reciprocating engine as claimed in claim 1 in which the oil return means on the intake valve means comprises a series of pockets in the surface of the valve means corresponding in number to the number of intake ports, said pockets opening through the end of the valve adjacent the crankshaft into the valve chamber and a passage connecting the valve chamber with a crankcase surrounding the crankshaft.

6. A two cycle reciprocating engine as claimed in claim 1 in which the oil return means on the exhaust valve means comprises a series of pockets in the surface of the valve means corresponding in number to the number of exhaust ports, said pockets communicating with oil receiving pockets in the outer Wall of the cylinder chamber when the valve means is in a partially retracted position whereby the oil is blown out of the valve pockets through the cell receiving pockets into the valve chamber, and a passage connecting the valve chamber with a crankcase surrounding the crankshaft.

7. A two cycle reciprocal engine comprising an elongated cylinder chamber, a pair of pistons in said chamber mounted for reciprocation in opposite ends thereof, a pair of substantially parallel crankshafts connected to and operated by each of said pistons, a series of exhaust ports spaced apart around the cylinder chamber adjacent one end thereof, said ports being closed by one of the pistons when the piston approaches the point of maximum entry into the cylinder chamber, a series of intake ports spaced apart around the cylinder chamber adjacent the end of the cylinder chamber opposite the exhaust ports, said ports being closed by the other of said pistons when said piston approaches the position of maximum entry into the cylinder chamber, positively driven means forcing the fuel and air mixture through the intake ports when the piston adjacent said ports is retracted from its position of maximum entry in the cylinder chamber, positively driven means exhausting the spent gases from the exhaust ports when the piston adjacent said ports is retracted, valve means reciprocable along the outer wall of the cylinder chamber alternately to open and close the exhaust ports, cam means on the crankshaft adjacent the exhaust port end of the cylinder advancing and retracting said valve means, valve means reciprocable along the outer wall of the cylinder chamber alternately to open and close the intake ports and cam means on the crankshaft adjacent the intake port end of the cylinder advancing and retracting said valve means, said cam means being timed so that the exhaust valve opens the exhaust ports before the intake valve opens the intake ports and closes the exhaust ports before the intake piston closes the intake ports on each stroke of the pistons.

8. A two cycle engine as claimed in claim 7 in which the positively driven means on the intake and exhaust manifolds are centrifugal pumps driven by a common shaft connected to one of the engine crankshafts.

9. A two cycle engine as claimed in claim 7 in which the valve means at both the exhaust and intake ports are sleeve valves driven from paired cam surfaces on the two crankshafts.

10. In a two cycle reciprocating engine having an elongated cylinder chamber, a pair of pistons in said chamber mounted for reciprocation in opposite ends thereof on parallel crankshafts, a series of exhaust ports at one end of the cylinder spaced around the circumference and a series of inlet ports at the opposited end of the cylinder spaced around the circumference thereof, the improvement comprising valve means reciprocable along the outer Wall of the cylinder alternately to open and close the exhaust ports, cam means on the crankshaft adjacent the exhaust port end of the cylinder advancing and retracting said valve means, valve means reciprocable along the outer Wall of the cylinder alternately to open and close the intake ports and cam means on the crankshaft adjacent the intake port end of the cylinder advancing and retracting the valve means, said cam means being timed so that the exhaust valve opens the exhaust ports before the intake valve opens the intake ports and closes the exhaust ports before the intake piston closes the intake ports on each stroke of the piston.

11. An improvement in two cycle engines as claimed in claim 10 in which the valve means are provided with oil return means and the cylinder walls are provided with means receiving the oil return means and conveying it to the respective crankcase.

HARLAN N. FISER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,168,877 Froelich June 18, 1916 1,221,337 Krill Apr. 3, 1917 1,879,910 Robertson Sept. 27, 1932 2,036,941 Hoover Apr. 7, 1936 2,099,983 Lake Nov. 23, 1937 2,112,829 Colburn Apr. 5, 1938 2,342,410 Lieberherr Feb. 22, 1944 FOREIGN PATENTS Number Country Date 658,891 France Jan. 28, 1929 

